Idiopathic Anaphylaxis Frequently Asked Questions (FAQ)

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Q 1: How is idiopathic anaphylaxis different to anaphylaxis?

Idiopathic is a medical term that is used to describe a disease or condition that has no known cause.

Anaphylaxis is a potentially life threatening, severe allergic reaction that usually occurs after exposure to a known allergen, such as a food, drug (medication), or insect. Information about anaphylaxis symptoms is on the ASCIA website   

Idiopathic anaphylaxis is a rare disorder that results in reactions that are similar to other forms of anaphylaxis, but a cause cannot be found. Reactions as a result of idiopathic anaphylaxis are triggered within the body for reasons that are not understood and are not due to any specific trigger outside the body.

Q 2: How is idiopathic anaphylaxis diagnosed?

Idiopathic anaphylaxis is diagnosed only after your doctor excludes possible causes of reactions, including allergens and diagnoses of other medical conditions that can mimic anaphylaxis.

Your doctor will usually take a detailed medical history and do a physical examination. To assist with the medical history, the ASCIA Anaphylaxis Event Record form can be used record symptoms, features of reactions and factors that can affect severity of reactions.  

This form is available on the ASCIA website

Your doctor may sometimes do skin prick testing and allergen challenge tests, or order blood tests for specific IgE antibodies to allergens and serum tryptase.

Information about allergy testing is on the ASCIA website

Q 3: How is idiopathic anaphylaxis treated?

A reaction due to idiopathic anaphylaxis should be treated as a medical emergency, in the same way as other forms of anaphylaxis. Adrenaline (epinephrine) injected into the muscle of the mid-outer thigh is first line treatment.

For people who have frequent reactions due to idiopathic anaphylaxis (such as six or more times per year), other treatments may be considered to help prevent reactions. If the frequency of reactions slows down, regular use of these treatments may be reduced or stopped.

Q 4: How is idiopathic anaphylaxis managed?

People who have frequent reactions as a result of idiopathic anaphylaxis need ongoing management by a doctor, which should include:

  • Referral to a clinical immunology/allergy specialist
  • Adrenaline injector prescription (EpiPen® or Anapen®).
  • ASCIA Action Plan for Anaphylaxis to provide guidance on when and how to use adrenaline injectors.
  • Regular follow up visits to a clinical immunology/allergy specialist.
  • Ways for you to manage stress that may be caused by not being able to know what triggers to avoid.

Further information is available at and from patient support organisations, Allergy & Anaphylaxis Australia and Allergy New Zealand

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ASCIA is the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand.

Content created May 2022

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